<template>
  <div class="xtx-city" ref="target">
    <div class="select" @click="toggle()" :class="{active:visible}">
      <span v-if="!fullLocation" class="placeholder">{{placeholder}}</span>
      <span v-else class="value">{{fullLocation}}</span>
      <i class="iconfont icon-angle-down"></i>
    </div>
    <div class="option" v-if="visible">
      <div v-if="loading" class="loading"></div>
      <template v-else>
        <span class="ellipsis" @click="changeItem(item)" v-for="item in currList" :key="item.code">{{item.name}}</span>
      </template>
    </div>
  </div>
</template>
<script setup>
import { computed, reactive, ref, defineProps, defineEmits } from 'vue'
import { onClickOutside } from '@vueuse/core'
import axios from 'axios'
  const emit = defineEmits()
  const props = defineProps({
    fullLocation: {
      type: String,
      default: ''
    },
    placeholder: {
      type: String,
      defulat: '请选择配送地址'
    }
  })
  // 显示隐藏数据
  const visible = ref(false)

  // 所有省市区数据
  const allCityData = ref([])
  // 正在加载数据
  const loading = ref(false)

  // 提供打开和关闭函数
  const open = () => {
    visible.value = true
    // 获取地区数据
    loading.value = true
    getCityData().then(data => {
      allCityData.value = data
      loading.value = false
    })
    // 清空之前选择
    for (const key in changeResult) {
      changeResult[key] = ''
    }
  }
  const close = () => {
    visible.value = false
  }
  // 提供一个切换函数给select使用
  const toggle = () => {
    visible.value ? close() : open()
  }
  // 实现点击组件外部元素进行关闭操作
  const target = ref(null)
  onClickOutside(target, () => {
    // 参数1：监听那个元素
    // 参数2：点击了该元素外的其他地方触发的函数
    close()
  })

  // 实现计算属性：获取当前显示的地区数组
  const currList = computed(() => {
    // 默认省一级
    let list = allCityData.value
    // 可能：市一级
    if (changeResult.provinceCode && changeResult.provinceName) {
      list = list.find(p => p.code === changeResult.provinceCode).areaList
    }
    // 可能：县地区一级
    if (changeResult.cityCode && changeResult.cityName) {
      list = list.find(c => c.code === changeResult.cityCode).areaList
    }
    return list
  })

  // 定义选择的 省市区 数据
  const changeResult = reactive({
    provinceCode: '',
    provinceName: '',
    cityCode: '',
    cityName: '',
    countyCode: '',
    countyName: '',
    fullLocation: ''
  })
  // 当你点击按钮的时候记录
  const changeItem = (item) => {
    if (item.level === 0) {
      // 省
      changeResult.provinceCode = item.code
      changeResult.provinceName = item.name
    }
    if (item.level === 1) {
      // 市
      changeResult.cityCode = item.code
      changeResult.cityName = item.name
    }
    if (item.level === 2) {
      // 地区
      changeResult.countyCode = item.code
      changeResult.countyName = item.name
      // 完整路径
      changeResult.fullLocation = `${changeResult.provinceName} ${changeResult.cityName} ${changeResult.countyName}`
      // 这是最后一级，选完了，关闭对话框，通知父组件数据
      close()
      emit('change', changeResult)
    }
  }
  // 获取省市区数据函数
  const getCityData = () => {
    // 数据：https://yjy-oss-files.oss-cn-zhangjiakou.aliyuncs.com/tuxian/area.json
    // 1. 当本地没有缓存，发请求获取数据
    // 2. 当本地缓存，取出本地数据
    // 返回promise在then获取数据，这里可能是异步操作可能是同步操作
    return new Promise((resolve, reject) => {
      // 约定：数据存储在window上的cityData字段
      if (window.cityData) {
        resolve(window.cityData)
      } else {
        const url = 'https://yjy-oss-files.oss-cn-zhangjiakou.aliyuncs.com/tuxian/area.json'
        axios.get(url).then(res => {
          // 缓存
          window.cityData = res.data
          resolve(res.data)
        })
      }
    })
  }
</script>
<style scoped lang="less">
.xtx-city {
  display: inline-block;
  position: relative;
  z-index: 400;
  .select {
    border: 1px solid #e4e4e4;
    height: 30px;
    padding: 0 5px;
    line-height: 28px;
    cursor: pointer;
    &.active {
      background: #fff;
    }
    .placeholder {
      color: #999;
    }
    .value {
      color: #666;
      font-size: 12px;
    }
    i {
      font-size: 12px;
      margin-left: 5px;
    }
  }
  .option {
    width: 542px;
    border: 1px solid #e4e4e4;
    position: absolute;
    left: 0;
    top: 29px;
    background: #fff;
    min-height: 30px;
    line-height: 30px;
    display: flex;
    flex-wrap: wrap;
    padding: 10px;
    > span {
      width: 130px;
      text-align: center;
      cursor: pointer;
      border-radius: 4px;
      padding: 0 3px;
      &:hover {
        background: #f5f5f5;
      }
    }
    .loading {
      height: 290px;
      width: 100%;
      background: url(../assets/images/loading.gif) no-repeat center;
    }
  }
}
</style>
